Tool for grinding conical bearings



1N VENTOR A TT NE Y Sept. 15, 1936. G. w. HoLcoMB l TOOL FOR GRINDING CONICALABEARINGS Filed Nov. 13, 1935 Patented Sept. 15, 1936 UNITED l OFFIQE Vroon FOR GRINIIIONICAL BEARINGS l v Application November 13, 1935, Serial No. 49,525

' 1o Claims. (o1. 51-236) This invention relates to-watch makers tools and has for its-object to provide a hand tool by means of which conical centerrbearings may be accurately ground on the end of pivot pins such as balance staffs etc. A

Another object of this invention is to so construct the tool that it may be adjusted to a Wide range of sizes of balance staffs and balance wheels for'regrinding the conical ends of the balance staffs. Y

A further object of this invention is to construct the tool so as to provide an absolutely free and axially true rotation of the staff during the grinding operation.

All these and other objects of this invention and attendant advantages will become more clearly apparent from the detailed description of it which follows, reference being had to the accompanying drawing in which 'i Figure l is a top plan View of the tool.

Figure 2 is a front elevation thereof.

Figure 3 is a side elevation of the tool with a balance wheel and staff mounted therein and held against a grinding wheel to have the conical bearing of the staff accurately regroundV thereon.

Figure 4 is an enlarged vertical sectional view of the upper portion of the tool with a balance wheel and staff mounted thereon, the section of the tool being taken on the line '4x- 4x of Figure 3.

tool illustrated in Figure 4.

Figure 6 is a horizontal section of the enlarged tool taken on the line Esc- 62: of Figure 4.

In the several figures of the drawing like reference numerals indicate like parts. j

The hand tool forming the subject matter of my present invention is especially adapted for use in accurately regrinding or refinishing therconical bearing ends of balance staffs carrying the balance wheel of watches, clocks etc. and the novel construction of the tool makes it possible to .perform this operation with precision and Without the aid of a machine tool such `asa lathe. l

4 As illustrated in the several figures of the draw'- ing the tool comprises a substantially rectangular frame l which is split at one end in the middle thereof to provide a pair of opposing jaws'Z and 3 at the end of the frame. The frame l is prefer- 50 ably formed up of spring metal stock so as to make the sides thereof yieldable and normally cause the jaws 2 and 3 to be yieldingly held against each other. The jaws are suitably tapered toward their ends as illustrated in Figures 1 and 5 and in the edge of each of the jaws is provided a triangular recess 6 so that the recesses of both of the jaws together form a substantially rhombically shaped opening between them.

The closed end 4 of the frame l is provided with a hole 5 thru which projects the hollow stem 1 VFigure 5 is a top plan view of the enlarged to have the frame l rest on the shoulder 8 thereof and be clamped thereto by means of the lock nut '9. The frame is thus xed on the hollow stem which is threaded on the inside to have the supporting stem l0 threaded therethru and provide an adjustable extension thereof. The outer end of Ythis supporting stem is suitably mounted in a hollow handle Il so that the'stem maybe rotated by means of this handle and suitably adjusted in the frame l.

For the purpose of locking the supporting stern Hl after it has been adjusted in the frame I, the h ollo-w stem 'l' is threaded on the outside of the frame and is provided with a tapered end which is split to make it contractible so that the outer opening inthe locknut I2 threaded' on the hollow Stem can engage and contract the end of the hollow stem and grip the supporting stem to keep it from rotating therein.

' The sides of the frame I are spread to move the jaws '2 and 3 by means of the spreading member I3. This member comprises a preferably flexible cross bar which is bifurcated at the ends to engage the inside andthe edges of the frame to keep it in engagement therebetween. In the middle of the cross bar is provided a hole I4 thru which projectsl the hollow stem 'l with the adjusting nut l5 threaded thereon to have this nut movable against the spreading member and force this member down the inwardly curved lower ends of the sides of the frame to cause these sides to spread.

The handle ll is preferably made hollow vand within itV may be mounted a removable .screw driver or other suitable tool.

The tool is used as follows: f

The balance wheel. is inserted into the frame l by forcing one end of the balance staff thru the rhombically shaped opening provided between the jaws 2 and 3 thereof to cause these jaws to spread and yieldingly grip the staff and hold it centered between the triangular recesses therein. With the staif held between the jaws, the

Vopposite end ofthe staff' is centered in the female conical bearing Il provided in the end of the supporting stem l0 s'o as to place the staifin perfect axial alignment with the supporting stem. The supporting stem is then adjusted in the frame to move the stai to a position in which the free end of thestaif projects a suitable distance from the staif from the center bearing in the supporting stem except when this stem is deliberately moved away from it to permit the stai to'be moved into the frame Vfor adjustment purposes. For the grinding operation Athe staff with the Y balance wheel Vis then released fromrthe Vpressure between them in an axially true rotation. l. ,f Yis done by movingthe'adjusting nut l5 against ofthe jawsV topermit the staff to `freely rotate the spreading member l3to cause this member to gradually force the sides of .the frame out-w wardly until the jawsr2 and 3"thereof Vretain butV a very slight frictional engagement withgthe 'stafL by means of the edges ofV their triangular recesses.v

In this way the stair is `kept centered inthe recesses and the friction of the jaws removed from it to allow thel staff Yto freely rotate between the Y jaws Ywhile being held tofa true axial rotation by its engagement with the centerbearringwin the end of the supporting stemY Il); Y Y v 'The'staff is then ready forvgrinding which is doner'rby holding the tool so as to present the free conical bearing end of the staff at the Yproper angleY to 'theV grinding surface of theY wheelY and cause the frictional contact'of the,grindingsur Vface to rotate the stati during thegrinding op-V eration in Yorder'to produceY an accurately centered conical bearing on the staif The process isrepeat'ed Vfor the conicalV bearing atthe opposite end of the staif to renish vboth bearings and make them rotate axially true when mounted in.

ance staff centered therein,'a holding frame surf. Vrounding said,stemrecessed spring jaws carried by saidframe to form a friction bearingV above said conical bearing to yieldingly embrace the balance staff supported in the center bearlng'and hold it in line with said stem, and means for rey leasing the yielding pressure of said spring jaws Y frame, a female center' bearing inthe endi of said Y stem within said Yframe to pivotally Vsupport the on the balance staff to permit a free andaxially true rotation of the staff between the spring jaws and the center bearing.

2; Artool for grinding conical bearings on balance staffsrand other pivot pins comprising. a

holding frame, a stem movable endwise in said end of a balance staff therein, recessed spring jaws carried by said frame to'form a friction bearing above said center'bearing to yieldingly em- Y brace the balance staff andlhold it inthe center jeo bearing in line with said stem and means for spreading said jaws to release the'pressure of the jaws on Vthe balance staiffand permita free and axially true rotation. of the staff between `said j aws andthe end of said stem'.`

3; VA toolfforgrinding conical bearings on bal- ,V ance staffs and other pivot pins comprisingfa Yspring frame, recessed gripping'njaws provided on said frame;Y a stemY threaded 'in oneY end of Y said frame so as to be movable towardY and away from said gripping jaws,V a female center bearing c in the end of said stern'withinV said spring frame,

a spreadingmember movable on saidstem within said'frame'to spread said framehand gradually separate said jaws. Y

Y LA tool for grinding conical bearingsV of Vbalance V.staffs and other pivot pins comprisingr a y' spring trarne,V a pair of `recessed jaws provided This at one end of said frame normally engaging each other to provide an expansible bearing between said sleeve to vmove endwise therein, a female;

center bearing in the end o'fcsaid supporting stem vv Within said frame and a handle on. said stem on the outside of said frame and means movable on il said sleeve Vand` engaging said frame to move said jaws and cause said expansible bearing to in- 'creas'e'or decrease in size.

f f 5':- vA tool as setforth in claim 4 including meansk for contracting said sleeve to adjustablyv lock said threaded stern into said sleeve.

i 6. AY tool for grindingconlcal bearings, of bal-Y Y Y yielding sides, jaws atY the free ends of said sides normally abutting each other with triangular ref cesses in each of said jaws forming a substantially rhombically shapedl opening between them, a supporting bearing within said frame to pivotf ally support Va balance stai within the frame with the staff clamped between the recesses in saidjaws and means for expanding the sides of 'saidV frame to spread said jaws to release their pressure on the balance staff until freely and axially rotatable in said triangular recesses with the stai pivotally supported `at Yone end in said supporting bearing and projecting from said frame with the other end. v V'7. A tool for grinding conical Ybearings of balance staffs and other pivot pinsas set Yforth inv claim 6 in which said jaws tapertoward the triangularrecesses therein to reduce their gripping surfaces to'substantiallyV the width'of thev Vre-Y Y cesses. i Y Y 8'. AA tool for grinding conical bearings of balance staffs andY other pivotV pins comprising a threaded c ontractible sleeve, a supporting stern threaded thru Vsaid sleeve, a clamping nut threaded on/the Voutside of said sleeve vto contract it Yand'lockrsaid supporting stem against movement in' said sleeve, a substantially rectangular 'and split frame supported on'said sleevelwith one end thereof, a lock nutV threadedon said sleeve 'and engaging Vsaid frame to hold said frame on Y said sleeve, a spreading member 'extending across said frame on'the inside thereof with said'sleeve `v provided with oppositely located triangular re-VY 'cesses so as to vhave the opening provided thereby axially in line with 'said supporting stem and a female center bearing in the end of said stem to support they endrof a balance staff on said supporting4 stemand have the f staff project thru the opening provided by said triangular recesses between the split end of the frame. r

v 10. A'tool as set forth ln'claimY 8in whichthe spreading memberis bifurcated at the ends to embrace the sidesrof'the frame` and hold the.

spreadingY member in engagementwithlthe frame and cause the frame to guide the spreadingmemberin its-movement. GEORGE W- .HOLCQMBf 

